you certainly could use the api to do something like this but in order to get the data in a form that will give you the points you want your min/max window would have to be from 1970 to 2050.
Except for the most obscenely reputed users this should not be an issue.
Alternately, if you don't mind doing this interactively, you could simply get your rep dump and parse it out.
This is obviously keyed to your cookie, so, as i said, it would have to be an interactive process.
I will bang out another simple usage example for Soapi.JS that will get you started.